1. Field of the Invention
This invention relates to a mechanically operated bellows pump comprising a suction line and pressure line respectively communicating with the interior of the bellows through a suction valve and a pressure valve.
2. Description of the Related Art
The metering of liquid dishwashing and clothes washing preparations or rinsing aids for domestic machines or sinks is normally done by hand using measuring cups, lids, caps, or the like. Similarly, the metering of chemical preparations in the laboratory or in manufacturing is also frequently done by hand. Accordingly, contact between the chemical product in question and the skin cannot always be ruled out. In addition, the particular quantity measured depends very much on the person doing the measuring. For this reason, hand-operated metering pumps were introduced. In their case, the particular measured quantity is usually determined by the number of strokes. Unfortunately, the operator can easily miscount the number of strokes so that, once again, too much or too little product is dispensed. Moreover, conventional metering pumps which are generally in the form of piston pumps show a tendency towards rapid wear at the sealing elements and hence towards incorrect metering or failure.